These tribes being in the Isles and being Pre-Roman and Pre-Anglo-saxon, I'd say as far as y-signatures are concerned the majority will belong to L21 and subclades. With DF27 and subclades rounding out the lower end of percentages. Then of course P312* people will make an appearance here and there, but their numbers seem to be giving way to DF27.

I kinda agree with U152 only really making an impact post Roman and Germanic invasions. Its mostly confined to the east with all of the other "invader" haplogroups. As you move west L21 becomes thick and very concentrated.

DF27 seems to be more common in the South and Southwest areas of England and Ireland reflecting more recent waves of migration, but still ancient in my opinion. It seems more sporadic in Scotland. Possibly due to Scandinavian invasions? L165 still puzzles me.

Then you have the Scottish RoxCluster which I'm thinking is DF27, Z196-.. Thats more associated with the Lowlands and Borders and in the areas of the tribes you mentioned. Though they'll still have an L21 majority.